The present invention relates to an improved air drier which is used to make humid and filthy air dried and cleaned by way of an air condenser and a cylinder shaped shell having a duct disposed therein which is provided with an air outlet tube for the cleaned and dried air to be discharged therefrom. The outer wall of the duct is provided with a continuous partition board attached thereto in a helix manner with the elongated condensing tube of a condenser disposed helically along the outer wall and in conformance to the helical partition board so that humid and dirty air pumped into the cylinder shaped shell and whirlingly led through the space defined by the helically wound partition board at a fast speed are in collision against the walls of the duct and the shell, resulting in the moisture particles and the dirt particles of the air filtered out and the condensed water dripping down along the walls thereof and collected at the conical bottom of the shell.
As shown in FIG. 1, a conventional air drier is used to make humid air dried by condensing the moisture particles therein by way of a coolant 11 which circulates in a looped tube 12. The coolant 11 is compressed by a compressor 13 and is led through a condenser 14 and to a coolant drying unit 15 and further to a thermal exchanger 18 and finally returns to the compressor 13. A fan 17 is used to cool off the coolant 11 and the pressure of the coolant is controlled by a pressure control valve 16. As humid air enters the thermal exchanger 18 by way of an air inlet port 181, the moisture particles contained therein are condensed into water via the coolant 11. The water and the air with some dirt particles are discharged via an outlet port 182 disposed at the top of the thermal exchanger 18 with water discharged via a water discharging unit 19. The problem is that the dust or dirt particles are easily mixed with the dried air and discharged into the surroundings.